Fix incorrect use of syn::exports (#7838)

* Fix incorrect use of syn::exports

Instead of using `syn::exports` we should import the trait from the
quote crate directly.

* Use own macro for test cases to fix compilation with latest syn

* Fix test

substrate/frame/support/procedural/Cargo.toml

@@ -19,7 +19,7 @@ frame-support-procedural-tools = { version = "2.0.0", path = "./tools" }
 proc-macro2 = "1.0.6"
 quote = "1.0.3"
 Inflector = "0.11.4"
-syn = { version = "1.0.7", features = ["full"] }
+syn = { version = "1.0.58", features = ["full"] }
 
 [features]
 default = ["std"]

substrate/frame/support/procedural/src/storage/parse.rs

@@ -47,7 +47,7 @@ mod keyword {
 pub struct Opt<P> {
 	pub inner: Option<P>,
 }
-impl<P: syn::export::ToTokens> syn::export::ToTokens for Opt<P> {
+impl<P: quote::ToTokens> quote::ToTokens for Opt<P> {
 	fn to_tokens(&self, tokens: &mut proc_macro2::TokenStream) {
 		if let Some(ref p) = self.inner {
 			p.to_tokens(tokens);

substrate/frame/support/procedural/tools/Cargo.toml

@@ -15,5 +15,5 @@ targets = ["x86_64-unknown-linux-gnu"]
 frame-support-procedural-tools-derive = { version = "2.0.0", path = "./derive" }
 proc-macro2 = "1.0.6"
 quote = "1.0.3"
-syn = { version = "1.0.7", features = ["full", "visit"] }
+syn = { version = "1.0.58", features = ["full", "visit"] }
 proc-macro-crate = "0.1.5"

substrate/frame/support/procedural/tools/derive/Cargo.toml

@@ -17,4 +17,4 @@ proc-macro = true
 [dependencies]
 proc-macro2 = "1.0.6"
 quote = { version = "1.0.3", features = ["proc-macro"] }
-syn = { version = "1.0.7", features = ["proc-macro" ,"full", "extra-traits", "parsing"] }
+syn = { version = "1.0.58", features = ["proc-macro" ,"full", "extra-traits", "parsing"] }